Method of making inner tubes



`Fume 26, 1945. J, w, WABER METHOD oF MAKING INNER TUBES Filed Feb. 19, 1943l 2 Sheets-Sheet l UUE/17701:.' James Z/Z [/Z/abgr.

`lune 26, 1945. wl wABER METHOD oF MAKING INNER TUBES 2 Sheets- Sheet 2 Filed F'eb. 19, 1945 HZT.

Patented June 26, 1945 UNITED .f (STATES PATENT OFFICE" .2,379,122 Y y METHOD F `MAKING IN NER VTUBES James W. Waber, Chicago, Ill. Application February 19, 1943, Serial No. 476,484

claims. (c1. 154-15) |This invention -relates to improvements in inner tubes'and particularly to the process of making a tube such as is commonly referred to as a puncture-proof tube, or more accurately as a self-sealing tube.

The present invention relates to a modification of .the tubes disclosed in applicants Patents 1,808,091, 2,033,962 and 2,161,490l `and may be made by the methods described in said patents, modified as indicated herein, although its -manulfacture is not limited tothe use of the :previously described methods.

The .present application is a continuation-.in- -part 4of applicants :former invention, ySerial No. 442,779, filed May 13, 1942, and the tube and method :differs from the tube of the above-noted .patents yand Patent 2,161,490, inparticular, in that the mastic, or unvulcanizable plastic material, is divided vtransversely as well as longitudinally vinto a plurality of sections by intervening partitions of vulcanizable material.

When self-sealing tubes, having plastic type vcfnnpounds in the tread portion thereof, are used in tires on vehicles that are driven continuously at 'exceedingly high speeds `for long `periods of time, there is a tendency for the ycentrifugal force to throwthe plastic material towardy the center line of the tube and away from the portion of the tube usually termed the shoulder, causing the plastic material to become of increased thickness at the center of `the tread portion and of less thickness atthe sides of the tread portion. This action is prevented by the partitions of vulcanizable material shown in Patent No.

When vehicles, provided with pneumatic tires, havingwself-sealing tubes, therein, are frequently subjected to sudden changes in speed, either by acceleration or deceleration, asin planes and motorized equipment of the army, there is a tendency to force they mastic material longitudinally, i. e., cireumferentially, of the tube and thus `cause the tube to have portions wherein the mastic is of less thickness? than normally. The tube herein disclosed is designed to prevent any substantial longitudinal movement ofthe mastic vcircumferentially of. the tube.

The object .of vthe present invention is to provide a method for producing a practical commercial rself-sealing tube of the above described character which will be cheap andr dependable and readily adaptable tofactory conditions of manufacture.

It maybe here noted that, due to the vnature ofv therplastic material, `displacement thereofy does not occur to any distinguishable degree vunder ordinary conditions of acceleration Yand deceleration or even at high speeds, when the periods of high speed are interspersed with a fair per,n centage of periods of average driving speed.

However, there are occasions when it is desirable to have an efficient self-sealing tube of -the plastic type that can be` successfully used under adverse lconditions and they present 'tube fulfills this requirement.

:It is `believed the further Idisclosure of` the invention will be readily understood from a vdetailed 'description thereof taken in4 connection with the accompanying drawings inwhich Fig. l1 shows a cross section of the tube which, so far as it appears in this gure, may be of substantially the same character as that shown in Patent No. 2,161,490;v

Fig. 2 is a perspective view ofa completed .tube with a portion of the external vcover layer ,removed to illustrate the arrangement of the transverse, as Well as 4longitudinal baffles of vulcanf izable material in the mastic at the tread portion thereof; .l

Fig. 3 shows a longitudinal section through a portion of the4 tread portion of the tube.; ,and

Figs. 4, 5, 6, '7 and-8 represent successive steps in carrying out applicants method as will clearly appear-from the following detailed description.,

Referring now to the drawings inr which like reference characters indicate the same parts in the several views:

The basic tube Il] ofvulcanizable material has applied -to the tread portion thereof a puncturesealing strip of mastic rcomprising the series of centrally positioned sections I Iv and the two series of lateral sections I2 and I2', one series -of lateral sections I2 being on one side of the strips II and the other series of lateral sections I2` being on the other side of the centralstrips II. overlying the strips II, I2, and I2 `is afcover strip I3, the opposite edges of which are vulcanized-to the basic tube 'III as shown in Fig. 1.

The sections lI I-, I2and I2' of the mastic'or sealing compound are separated by longitudinally extending baffles or partitions I4 and I4' "of vulcanizable material and alsoby the transversely extending partitions i5. lIn the mashed tube, each of the baffles or partitions I4, I4 and I5 has its inner edge lfixed by vulcanization to the basic tube I0 and its .outer edgesecured in like manner to the cover strip I3. It vwill thus be seen that any substantial movement of the sections II, I2, and I2' offmastic -is `prevented.

The `method of forming the tube will now be described. Upon a smooth surface, which is slightly longer than the circumference of the tube to be formed, is placed a sheet or strip I3 of vulcanizable material which is, preferably, a little wider than the self-sealing tread portion of the tube. (See Fig. 4.) Upon the strip I3 and trans- Versely thereof are placed strips I'I of similar vulcanizable material. The strips I1 will be arranged in substantially parallel relation and spaced apart any desired distance. In practice, it has been found to give a satisfactory tube if the strips II are placed ten to twelve inches apart. The best distance to space these strips will, however, vary somewhat due to variation in the consistency of the mastic and the character of service to which the tube is to be subjected. Although the use of strips I1 is desirable, a satisfactory tube, such as herein contemplated, may be made without usingv them.

Transversely of the strips I'I and substantially centrally of sheet I3, is placed a strip I I of mastic or unvulcanizable material, as shown in Fig. 5. This strip II is later separated into sections II of Fig. 2. As illustrated in Fig-6, there is next placed at the opposite sides of the strip Il of mastic, the strips I4 and I4' of vulcanizable material. The strips I4 and I4 are sulciently wide so that the inner edges thereof engage the strip I3 and the outer edges extend to, or slightly beyond the outer surface of the mastic strip'II so as to engage the base tube I when the tread portion is placed in position thereon, as hereinafter described. Thus, upon vulcanization of the tube, the edges of strips I4 and I4 become firmly vulcanized, respectively, to the basic tube IB and to the cover strip I3.

The next step in the process is to place the strips I2 and I2 of mastic at the outer sides of the strips I4 and I4', respectively, as shown in Fig. '7. The strips I2 and I2I later become the sections I2 and I2 of Fig. 2.

By means of either a slicing or shearing action, the strips II, I2 and I2 of mastic and the partitions I4 and I4 are severed along lines overlying the transverse strips I'I of vulcanizable material. These slits or cuts are successively formed and the transverse baiiles or partitions I5 are inserted respectviely therein. The baies I 5, of vulcaniza ble material, are arranged with their inner edges in contact with the strips .II, respectively, or in contact with sheet I 3 if strips I'I are not employed, and the outer edges extending to, or slightly beyond the outer surface of the mastic portion so as to engage the basic tube I0 when the tread portion (Fig. 8) is placed about the tread of the basic tube IU.

The rest of the process may be somewhat similar to that described in applicants previous patents, The basic tube I0 is inflated and mounted on a building Wheel. The built-up tread portion, composed of strips I3, I'I, II,.I2, I2', I4, and I4', as shown in Fig. 8, is then positioned about the periphery of the basic-tube, with the cover layer I3 outermost and with its lateral edges in engagement with the basic tube I0. The tube is now placed in a mold of the correct size and shape and vulcanized. During vulcanization, the pressure within the tube will be of such a degree as to insure that all the sections of vulcanizable material are brought into close contact at their meeting surfaces so that they will be iirmly vulcanized together and the tube'will be provided with a smoothly finished outer'surface.

Patent'No. 2,033,962 discloses the expedient of treating the tread portion of the basic tube I0 which underlies the cover layer, prior to vulcanization, with a vulcanization accelerator to insure a tight cure of this portion of the basic tube. The partitions, or baflies, I4, I 4 and I5 may be similarly treated.

The present disclosure shows but two longitudinally extending partitions, which in most cases are sufficient, but if the mastic is of a soft plastic consistency, it may be found desirable to separate the mastic into smaller sections. The process to be followed in such a case, however, will be similar to that hereinbefore described, it being merely necessary to supply additional longitudinally extending bailles and strips.

If the vehicle on which the tires are used is not driven at high speed, but is often subjected to rapid'acceleration and deceleration, it may be necessary to employ only the transverse bales.

While above, the tube has been described as preferably made on an air mandrel, it is believed lthat its manufacture is not limited to this expedient.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. The method of constructing an inner tube for pneumatic` tires which consists in forming a tread 'portion for said tube by placing upon a supporting surface a cover strip of vulcanizable material slightly longer and broader than the self-sealing tread portion of the tube to be formed, superimposing on said cover strip substantially centrally thereof longitudinally extending alternate strips of sealing compound and separator strips of vulcanizable material, severing said strips of sealing compound and separator stripsY transversely thereof at spaced intervals, insertingv transverse separator strips of vulcanizable material in the slits formed by such severing, said separator strips being arranged to contact the said cover strip at their lower edges and to extend to or beyond said sealing compound at their upper edges, expanding a basic endless tube of vulcanizable material by internal pressure, superimposing upon the periphery of said basic tube, while so expanded, the built up tread portion of said tube with said cover strip of vulcanizable material outermost and curing the whole tube structure, while expanded, in a mold to cause the vulcanizable cover strip to become vulcanized at its lateral edges to the basic tube and causing said separator strips to become vulcanized to said basic tube and to said cover strip at their opposite edges, respectively, and to each other at their points of intersection. I

2. The method of constructing an inner tube for pneumatic tires which consists in forming a tread portion for said tube by placing upon a supporting surface a cover strip of vulcanizable material slightly longer and broader than the self-sealing tread portion of the tube to be formed, superimposing on said cover strip substantially centrally thereof longitudinally extending alternate strips of sealing compound and separator strips of vulcanizable material, severing said strips of sealing compound and separator strips transversely thereof at spaced intervals, inserting. transverse separator strips of vulcanizable material in the slits formed by such severing, said separator strips being arranged to contact the said coverstrip at their lower edgesand to extend to or beyond said sealing compound at their upper edges, forming a basic endless` tube of` vulcanizable material, superimposing upon the periphery of said basic tube, the built up tread by internal pressure and curing the whole tube structure, while expanded, to cause the vulcanizable cover strip to become vulcanized at its lateral edges to the basic tube and causing said separator strips to become vulcanized to said basic tube and to said cover strip at their opposite edges, respectively, and to each other at their points of intersection.

3. The method of constructing an inner tube for pneumatic tires which consists informing a tread portion for said tube by placing upon a supporting surface a cover strip of vulcanizable material slightly longer and broader than the self -sealing tread portion of the tube to be formed, placing on said cover strip at intervals and transversely thereof narrow strips of vulcanizable material, superimposing on said base strip and transverse strips and substantially centrally thereof longitudinally extending alternate strips of sealing compound and separator strips of vulcanizable material, severing said strips of sealing compound and separator strips along lines overlying said narrow strips of sealing' compound, inserting transverse separator strips of vulcanizable material in the slits formed by such severing, said separator strips being arranged to contact the said cover strip and said transverse strips at their lower edges and to extend to or beyond said sealing compound at their upper edges, expanding a basic endless tube of vulcanizable material by internal pressure, superimposing upon the periphery of said basic tube, while so expanded, the built up tread portion of said tube with said cover strip of vulcanizable material outermost and curing the whole tube structure, while expanded, in a mold to cause the vulcanizable cover strip to become vulcanized to the basic tube at its lateral edges and causing said separator strips to become vulcanized to said basic tube and to said' cover strip at their opposite edges, respectively, and to each other at the points of their intersection.

4. The method of constructing, an inner tube for pneumatic tires which consists in forming a tread portion for said tube by placing upon a supporting surface a cover strip of vulcanizable material slightly longer and broader than the selfsealing tread portion of the tube to be formed, placing on said cover strip at intervals and transversely thereof narrow strips of vulcanizable material, superimposing on said cover strip and transverse strips and substantially centrally thereof longitudinally extending alternate strips of sealing compound and separator strips of vulcanizable material, severing said strips of sealing compound and separator strips along lines overlying said narrow strips of vulcanizable material, inserting transverse separator strips of vulcanizable material in the slits formed by such severing, said separator strips being arranged to contact the said cover strip and said transverse strips at their lower edges and to extend to or beyond said said sealing compound at their upper edges, forming a basic endless tube of vulcanizable material, superimposing upon the periphery of said basic tube the built up tread portion of said tube with said cover strip of vulcanizable material outermost and curing the whole tube structure, while expanded, in a mold to cause the vulcanizable cover strip to become vulcanized, at its lateral edges, to the basic tube and causing saidseparator strips to become vulcanized to said basic tube and to said cover strip at their opposite edges, respectively, and to each other at their points of intersection.

5. The method of constructing an inner tube for pneumatic tires which consists in forming a tread portion for said tube by placing upon a supporting surface a cover strip of vulcanizable'material somewhat longer and wider than the selfsealing tread portion of the tube to be formed, superimposing on said cover strip and substantially centrally thereof a puncture-sealing strip consisting of alternate sections of sealing compound and transversely extending separator strips of vulcanizable material, said separator strips being arranged to contact the said cover strip at their lower edges and to extend to or beyond said sealing compound at their upper edges, forming a basic endless tube of vulcanizable material, placing said endless tube on a building wheel, superimposing upon the periphery of said basic tube, the built up tread portion of said tube with said cover strip of vulcanizable material outermost and curing the whole tube structure in a mold to cause the vulcanizable cover strip to become vulcanized to the basic tube at its lateral 

